package TEST4_21;

public class T1 {

    public static int sum(int n){
        if (n==1){
            return 1;
        }
        if (n==2){
            return 3;
        }
        return n+sum(n-1);
    }

}
class test1{
    public static void main(String[] args) {
        System.out.println(T1.sum(3));
    }
}
